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Generally speaking, there are three methods of calculating the bending stress on the barrel. The commonly used calculating methods for the bending stress of the barrel of the rotating kiln with more than three supporting point: 'three bending moment equation method' and 'torque distribution method'. The result of the former method is very acturate, but with the increasing of supporting points, the calculating methods will become more and more complicated for this reason, errors are easy to occur in the calculating process. The latter is suitable for many supporting points and it does not need to solve simultaneous equations, the computation is very easy and convenient and the final result is relatively accurate.

(1) Check and verification of the bending stress of the barrel: we usually use the following formula to compute it:

In the above formula, б refers to the axial bending stress; M refers to the section bending moment and W refers to the section modulus.

(2) Check and verification of the axis deflections. Because the radial deformation can not be computed so far, people still use the axis Y as one of the control indexes of the design of barrel. When the cross or cantilever period of deflection is max, the span is 1, the deflection allowable value is (y), it should meet the following requirements: ymax/l[y] = 0.3 mm/m.

The development trend of computing method. So far, the allowable applicable stress of the rotary kiln is very low in the design. As for A3 steel, the safety factor will reach as high as 8 to 11 or even higher. However, this cannot show that the design is conservative because the following factors are taken into consideration:

(1) There will be some discrepancy allowed on the axis when the kiln is installed. However, in the operational process of the kiln, the supporting position of various kinds of gears will be slightly different from the ideal state which may cause huge additional bending moment and counter force to the barrel.

(2) Because the actual carrying capacity of the barrel is very complicated which will bring difficulty for the computation. In the operational process of the kiln, the barrel will sustain two stress composed by axial and ring force at the same time. In addition, because the temperature stress caused by the temperature difference of the radial direction and axial direction, the final result will be different from the actual condition.

(3) Because the rotary kiln belongs to heavy machine and works under severe environment for a very long period of time, the service life of the barrel is generally about thirty years.

We can know from the production practice and theoretical calculation, the above calculating method cannot completely reflect the actual condition of the barrel. So far, the research work in our country is still under way and the experts are trying to find out a calculating method that is able to totally reflect the actual radial deformation theory through the analysis and research of theoretical computation and experiment stress and provide theoretical support for the significance of the manufacturing of rotary kiln. Hongxing Machinery has always lead in the mining machinery manufacturing industry, the machines such as ore beneficiation are well received by the customers.